City aims to maintain COVID-19 case downward trend

BAGUIO CITY – (Feb. 19, 2021) – Baguio City seeks to sustain the downward trend in its Coronavirus disease (COVID-19) cases observed in the past weeks.

Mayor Benjamin Magalong said that to achieve this, the city has to maintain if not intensify the health and safety protocols it had been implementing.
City Health Officer Dr. Rowena Galpo said the city’s statistics had improved based on the two-week growth rate (TGWR) and the average daily attack rate (ADAR).

The city’s ADAR from Jan. 31 to Feb. 14 was 4.7 percent which is below the threshold set by the World Health Organization (WHO) at 5 percent.  For the TGWR, the number of cases in the last two weeks was lower by 148 cases than that of the previous two weeks

The mayor said downtrend has also manifested in the number of case confinements in hospitals and isolation facilities in the city which considerably dropped effectively decongesting the facilities and providing a little breather for the medical front liners.

This was also shown in an ongoing University of the Philippines Baguio study of the city’s COVID-19 data which continues to interpret and map out the city’s COVID-19 data through various statistical data analyses of the city’s confirmed cases to establish patterns and relevant information on the COVID situation in the city.In its latest update, the team from the Department of Mathematics and Computer Science professors led by Prof. Rizavel Addawe which has been conducting the analyses said the city has registered an overall positivity rate is 4.25 percent which means that in every 100 persons to be tested, there are 4 persons who will have a positive result.”As recommended by WHO, attack rates and positivity rates should remain at or below 5 percent for at least 14 days. A rate higher than this means more people are getting infected,” the team said.

The team also said that the city has recorded a total of 125,590 tests done from March 2, 2020 to February 16, 2021 which represents 33.54 percent of the city’s population. In the study, the team has been considering frequency measures such as attack rate, doubling time, growth rate and moving averages as well as threshold values set by the WHO to assess the level of community transmission and see if the city can control the disease.

Daily Attack RateThe daily attack rate (proportion of population that contracts the diseases in an at risk population at a given time) is computed by obtaining the ratio of the number of cases whose onset date is t and the total population of the area. According to the latest results of the study, “the seven-day moving average for the attack rate was recorded from February 5 to 11, 2021 with a rate of 5.0 percent per 1000, a value equal to the threshold value which is 5 percent per 1000 individuals.” 

“Meanwhile, the attack rate for February 11, 2020 is 4.9 percent per 1000 residents which means that about 5 individuals per 100,000 were confirmed to acquire the disease on that certain day. 

This rate is lower than the 7-Day Moving Average,” the study notes. Case Doubling Time”For the case-doubling time, or the number of days required for the number of cases to double, a higher number implies a slower doubling rate. An increase of doubling time implies that mitigation measures are being effective, while constant doubling time suggests growth of infection at a constant exponential rate,” the study noted.”Using these to describe the rate of infection in relation to its distribution based on sex, age, occupation, and severity, among others, reveal the possible trend of cases.

“For February 17, 2021, the doubling time of Baguio City is 28.50 days. The city’s doubling time means that the number of cases will double by approximately 29 days. There is a projection of 10,698 cumulative cases after 29 days if no interventions will occur. In the graph above, the doubling time gradually increases from the date the first case was confirmed. “Note that the number of cumulative cases has been increasing but the case doubling time also increases gradually.

This may be interpreted that the growth of cases can still be controlled. Note also that the case doubling time recorded from the first recorded cases is lower than 30 days, the target value for doubling time,” the team said

Two-Week Growth RateThe two-week growth rate (TWGR) is defined as the “rate of the increase or decrease in the number of infections and it captures how quickly the number of COVID infections is changing every two weeks.”It is computed by obtaining the difference between the total number of cases and the number of cases for the past 14 days divided by the number of cases in the last 14 days.As of February 15, 2021, the two-week growth rate is 4.01 percent implying that the total number of confirmed cases in the city has risen these past two weeks by 206 cases. 

“The 7-Day Moving Average from February 9 to 15, 2021 is 5.34 percent.

The average two-week growth rate for the said dates is higher than the actual number of two-week growth.  Trend is generally decreasing- both on the actual 2 week growth rate and its corresponding 7-day MA. However, it does not necessarily mean that cases are decreasing,” the study noted.

7-Day Moving Average
The 7-day moving average (MA) is computed by adding the total of cases for the past seven days divided by seven days and is used to “visualize the number of new COVID-19 cases and compute the rate of change.”“The MA on February 11, 2021 is 17 cases, a value lower than the cutoff of 19 cases and the actual number of 73 cases. It is the average from February 5 to 11, 2021. This average value implies that the total number of cases in the said week is 17×7 = 119 new cases.

This means that we may also expect about 119 new additional cases for the next 7 days (from Feb. 11),” the team said.The ongoing study entitled “Exploratory Data Analysis (EDA) of Baguio City COVID-19 Cases Daily Updates,” the UP Baguio-led research team has been recording daily COVID-19 updates in partnership with the City Health Services Office (CHSO) to interpret and map out the city’s COVID-19 data since March 2, 2020 through various statistical data analyses of the city’s confirmed cases with the aim of establishing patterns and relevant information on the COVID situation in the city.Apart from Corsino, the study team is composed of Jhunas Paul Viernes, Wilfredo Dizon Jr., Shielden Grail Domilies, Criselda Libatique, Joseph Ludwin Marigmen, Raya Elaine Gueco, R. R. Oryan and Donnabel Tubera-Panes. – Aileen P. Refuerzo